Feeding the pregnant sow
A few days before birth monitor the food as if overfed the sow can become constipated and her gut distended. This can result in constriction of the reproductive tract, giving problems to farrowing.
Watch out for scouring (diarrhoea) as this can lead to dehydration, which can make the milk production more difficult.
Feed a little less over the three days before the birth, being careful not to totally alter the feeding routine. Exercise also prevents them from becoming too heavy and grass is a source of roughage. It is true that there is little nutrients in grass but it is an aid to their wellbeing.